Multiple Beamforming with Perfect Coding

Perfect Space-Time Block Codes (PSTBCs) achieve full diversity, full rate, nonvanishing constant minimum determinant, uniform average transmitted energy per antenna, and good shaping. However, the high decoding complexity is a critical issue for practice. When the Channel State Information (CSI) is available at both the transmitter and the receiver, Singular Value Decomposition (SVD) is commonly applied for a Multiple-Input Multiple-Output (MIMO) system to enhance the throughput or the performance. In this paper, two novel techniques, Perfect Coded Multiple Beamforming (PCMB) and Bit-Interleaved Coded Multiple Beamforming with Perfect Coding (BICMB-PC), are proposed, employing both PSTBCs and SVD with and without channel coding, respectively. With CSI at the transmitter (CSIT), the decoding complexity of PCMB is substantially reduced compared to a MIMO system employing PSTBC, providing a new prospect of CSIT. Especially, because of the special property of the generation matrices, PCMB provides much lower decoding complexity than the state-of-the-art SVD-based uncoded technique in dimensions 2 and 4. Similarly, the decoding complexity of BICMB-PC is much lower than the state-of-the-art SVD-based coded technique in these two dimensions, and the complexity gain is greater than the uncoded case. Moreover, these aforementioned complexity reductions are achieved with only negligible or modest loss in performance.Comment: accepted to journa

A Novel Adaptation of a Parent-Child Observational Assessment Tool for Appraisals and Coping in Children Exposed to Acute Trauma

Background: Millions of children worldwide are exposed to acute potentially traumatic events (PTEs) annually. Many children and their families experience significant emotional distress and/or functional impairment following PTEs. While current research has begun to highlight a role for early appraisals and coping in promoting or preventing full recovery from PTEs, the exact nature of the relationships among appraisals, coping, and traumatic stress reactions as well as how appraisals and coping behaviors are influenced by the child\u27s environment (e.g., parents) remains unclear; assessment tools that reach beyond self-report are needed to improve this understanding. Objective: The objective of the current study is to describe the newly created Trauma Ambiguous Situations Tool (TAST; i.e., an observational child–parent interview and discussion task that allows assessment of appraisals, coping, and parent–child processes) and to report on initial feasibility and validation of TAST implemented with child–parent dyads in which children were exposed to a PTE. Method: As part of a larger study on the role of biopsychosocial factors in posttraumatic stress reactions, children (aged 8–13) and parents (n=25 child–parent dyads) completed the TAST during the child\u27s hospitalization for injury. Results: Children and parents engaged well with the TAST. The time to administer the TAST was feasible, even in a peri-trauma context. The TAST solicited a wide array of appraisals (threat and neutral) and coping solutions (proactive and avoidant). Forced-choice and open-ended appraisal assessments provided unique information. The parent–child discussion portion of the TAST allowed for direct observation of parent–child processes and demonstrated parental influence on children\u27s appraisals and coping solutions. Conclusions: The TAST is a promising new research tool, which may help to explicate how parents influence their child\u27s developing appraisals and coping solutions following a PTE. More research should examine the relationships of appraisals, coping, and parent–child processes assessed by the TAST with traumatic stress outcomes

Delay-Tolerant Decode-and-Forward Based Cooperative Communication over Ricean Channels

International audienceIn this paper, we propose a TDMA based simple transmission scheme, which overcomes the effect of the delays caused by the poor synchronization of the relaying nodes over Ricean channels. The proposed scheme is able to provide an optimized coding gain in unsynchronized cooperative networks as compared to the existing delay tolerant distributed space-time block codes

Test-Time Adaptation via Self-Training with Nearest Neighbor Information

Adapting trained classifiers using only online test data is important since it is difficult to access training data or future test data during test time. One of the popular approaches for test-time adaptation is self-training, which fine-tunes the trained classifiers using the classifier predictions of the test data as pseudo labels. However, under the test-time domain shift, self-training methods have a limitation that learning with inaccurate pseudo labels greatly degrades the performance of the adapted classifiers. To overcome this limitation, we propose a novel test-time adaptation method Test-time Adaptation via Self-Training with nearest neighbor information (TAST). Based on the idea that a test data and its nearest neighbors in the embedding space of the trained classifier are more likely to have the same label, we adapt the trained classifier with the following two steps: (1) generate the pseudo label for the test data using its nearest neighbors from a set composed of previous test data, and (2) fine-tune the trained classifier with the pseudo label. Our experiments on two standard benchmarks, i.e., domain generalization and image corruption benchmarks, show that TAST outperforms the current state-of-the-art test-time adaptation methods

Distributed space-time block codes for two-hop wireless relay networks

Recently, the idea of space-time coding has been applied to wireless relay networks wherein a set of geographically separated relay nodes cooperate to process the received signal from the source and forward them to the destination such that the signal received at the destination appears like a Space-Time Block Code (STBC). Such STBCs (referred to as Distributed Space-Time Block Codes (DSTBCs)) when appropriately designed are known to offer spatial diversity. It is known that different classes of DSTBCs can be designed primarily depending on (i) whether the Amplify and Forward (AF) protocol or the Decode and Forward (DF) protocol is employed at the relays and (ii) whether the relay nodes are synchronized or not. In this paper, we present a survey on the problems and results associated with the design of DSTBCs for the following classes of two-hop wireless relay networks: (i) synchronous relay networks with AF protocols, (ii) asynchronous relay networks with AF protocols (iii) synchronous relay networks with DF protocols and (iv) asynchronous relay Fig. 1. Co-located MIMO channel model networks with DF protocols

A Bibliometric Analysis of the Intellectual Structure of Studies on Slavery in the 21st Century

Objective of the study: The aim of the article was to analyze the intellectual structure of publications on slavery within the scope of the Administration. To achieve this objective, the following research questions were proposed: What is the intellectual structure of recent publications on slavery in the business research area? How is the past of slavery remembered (or forgotten) in this century’s researches on business research area?Methodology/approach: We used the quantitative method of scientific mapping that combines bibliometrics and graphic representation. In this process, we extracted publications from the Scopus database and, then, grouped the references using the Bibexcel software. To identify the subgroups and create the visualization map, we used VOSviewer.Originality/Relevance: Slavery is generally considered to be the dark side of business practices, and for this reason, it is a topic that is still little explored in management research. The relevance of this study is to systematize the academic production of this sensitive topic and to offer scholars and practitioners in the area a detailed analysis of the theoretical foundation of studies on slavery.Main results: Results indicate that the intellectual structure of studies related to slavery can be grouped into nine pillars that cover several themes, such as heritage tourism, Critical Accounting, Management History and the perpetuation of the legacy of slavery in the globalized world.Theoretical/methodological contributions (mandatory): Analyzing the repressed memory of slavery in the context of management is necessary and a great opportunity for future research. It is undeniable that slavery is a part of History that cannot be overlooked and this study explores this latent gap in Management studies